1. Field
The present invention relates to a method for installing an elevator and to an elevator installed according to the method.
2. Description of Related Art
One of the objectives in elevator development work is to achieve an efficient and economical utilization of building space. In recent years, this development work has produced various elevator solutions without machine room, among other things. Good examples of elevators without machine room are disclosed in specifications EP 0 631 967 (A1) and EP 0 631 968. The elevators described in these specifications are fairly efficient in respect of space utilization as they have made it possible to eliminate the space required by the elevator machine room in the building without a need to enlarge the elevator shaft. In the elevators disclosed in these specifications, the machine is compact at least in one direction, but in other directions it may have much larger dimensions than a conventional elevator machine.
In these basically good elevator solutions, the space required by the hoisting machine limits the freedom of choice in elevator lay-out solutions. Some space is needed to provide for the passage of the hoisting ropes. It is difficult to reduce the space required by the elevator car itself on its track and likewise the space required by the counterweight, at least at a reasonable cost and without impairing the performance and operational quality of the elevator. In the case of a traction sheave elevator without machine room, mounting the hoisting machine in the elevator shaft is difficult, especially in a solution with machine above, because the hoisting machine is a sizeable body of considerable weight. Especially in the case of larger loads, speeds and/or hoisting heights, the size and weight of the machine are a problem regarding installation, even so much so that the required machine size and weight have in practice limited the sphere of application of the concept of elevator without machine room or at least retarded the introduction of said concept in larger elevators. In modernization of elevators, the space available in the elevator shaft has often limited the sphere of application of the concept of elevator without machine room. Often, especially when hydraulic elevators have had to be modernized or replaced, it has not been practical to apply a roped elevator solution without machine room due to insufficient space in the elevator shaft, particularly when no counterweight has been used in the hydraulic elevator solution to be modernized/replaced. The drawbacks of elevators with counterweight are the cost of the counterweight and the space required for the counterweight in the elevator shaft. Drum driven elevators, which are nowadays rather seldom installed, have the drawbacks of heavy and complicated hoisting machines and their large power and/or torque requirement. Prior-art elevators without counterweight are exotic and no proper solutions are known. So far it has not been technically or economically reasonable to make elevators without counterweight. One solution like this is disclosed in specification WO9806655. The recent international patent application PCT/FI03/00818 discloses a feasible elevator solution without counterweight differing from prior-art solutions. In prior-art elevator solutions without counterweight, the tensioning of the hoisting rope is implemented using a weight or spring, and that is not an attractive approach to implementing the tensioning of the hoisting rope. Another problem with elevators without counterweight, when long ropes are used e.g. due to a large hoisting height or large suspension ratios used, the compensation of rope elongations and at the same time the friction between the traction sheave and the hoisting ropes is insufficient for the operation of the elevator. In the case of a hydraulic elevator, especially a hydraulic elevator with lifting power applied from below, the shaft efficiency, i.e. the ratio of the cross-sectional shaft area taken up by the elevator car to the total cross-sectional area of the elevator shaft, is fairly high. This has traditionally been a significant reason why expressly a hydraulic elevator has been selected for a building. On the other hand, hydraulic elevators have many drawbacks related to their lifting principle and use of oil. Hydraulic elevators have high energy consumption, a possible leakage of oil from the equipment is an environmental hazard, the periodically required oil change involves a high cost, even an elevator installation in good condition causes olfactory disadvantages as small amounts of oil escape into the elevator shaft or machine room and from there further to other parts of the building and into the environment and so on. Due to the shaft efficiency of a hydraulic elevator, modernization of the elevator by replacing it with another type of elevator that would allow the drawbacks of the hydraulic elevator to be avoided but would necessitate the use of a smaller elevator car is not an attractive solution to the owner of the elevator. Hydraulic elevators also have small machine spaces, which may be located at a distance from the elevator shaft, making it difficult to change the elevator type.
There are very large numbers of traction sheave elevators installed and in use. They were made at their time to meet the proposed needs of users and the intended uses of the buildings concerned. Later, both user needs and the practical requirements of the buildings have changed in many cases and an old traction sheave elevator may have become insufficient in respect of size of the elevator car or in other respects. For example, older elevators of a rather small size are not necessarily suited for transporting perambulators or roller chairs. On the other hand, in older buildings that have been converted from residential use to office or other use, the originally installed smaller elevator is no longer sufficient in capacity. As is known, increasing the size of such a traction sheave elevator is practically impossible because the elevator car and counterweight already fill the cross-sectional area of the elevator shaft and the car can not be reasonably enlarged.